Seat reclining mechanism

ABSTRACT

A seat reclining mechanism comprises first and second hinge plates for mounting on a seat and a back-rest respectively, and an internally toothed ring gear on each of the hinge plates. One ring gear has more teeth than the other ring gear, and a drive gear extends within the two ring gears. Further provided are means for engaging the drive gear and the ring gears, which includes at least one planetary gear in mesh with both ring gears and the drive gear, and means for rotating the drive gear to effect relative angular adjustment of the two hinge plates. In another embodiment of the present invention a drive gear is within the space within the two ring gears, and a pair of carrier members sandwich the drive gear therebetween. The carrier members position and locate the one or more planetary gears, and further provide a floating nature to the operation of the mechanism which compensates for wear of the gears.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 940,965, filed May 8, 1978,now U.S. Pat. No. 4,211,451, which application is a continuation-in-partof application Ser. No. 781,103, filed Mar. 25, 1977 (now abandoned),which in turn is a continuation-in-part of application Ser. No. 653,659,filed Jan. 30, 1976 (now abandoned).

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a seat reclining mechanism

2. Description of the Prior Art

Seat reclining mechanisms are available for vehicle seats, which providefor angular adjustment of the seat proper and the backrest by rotationof a gear in a gear arrangement which is self-locking in the adjustedposition.

Such a mechanism is described in U.K. patent application No. 1,091,944.Its construction includes two hinged plates with an internally toothedring gear on one plate and a spur gear mounted for eccentric motion onthe other plate and engaged with the ring gear. Adjustment is achievedby a difference in the numbers of teeth on the two gears. A disadvantageof this construction is that the plates move eccentrically, thismovement being transmitted to the backrest, in use, the backrest makingwhat has been termed as "waltzing" movement.

Another construction of a seat reclining mechanism is described in U.K.Patent specification No. 1,170,708 to Recaro. Recaro's disclosureprovides a ring gear on each plate and two spur gears which are rotatedsimultaneously and eccentrically and engage respectively the two ringgears. This construction avoids the "waltzing" disadvantage, but is moreexpensive to produce. Another embodiment uses a small gear carried on anarm to engage the ring gears. This construction is insufficientlystrong, since a large force is carried by the teeth of a small gear. Thesmall gear or its carrying arm is liable to break, or the small gearwill be forced out of a locking position, so that the bracket collapses.

Disclosed in the German Patent specification No. 1,555,711 is anotherstructure of a seat reclining mechanism. This construction also has ringgears on the two hinge plates, but a gear carrier is provided mountingfour small gears on a circle. Each of these small gears is a compositegear formed of two integral gears having their teeth offset. Oneintegral gear of each of the four composite gears is engaged with onering gear and the other integral gear of each composite gear is engagedwith the other ring gear. The gear carrier is rotated so that thecomposite gears roll along the ring gears and rotation is achieved by afurther gear engaged with external teeth on the gear carrier. Thecomposite gears are very difficult to make and consequently veryexpensive as one of the integral gears contains eight teeth, while theother integral gear contains only seven teeth. Accordingly, it is alsoimpossible to use a single central control gear to engage fully both ofthe integral gears of each composite gear. This construction alsosuffers the disadvantage of having a total of twelve gears, includingthe carrier, making the mechanism as a whole very expensive to produce.

U.S. Pat. No. 3,972,563 to Gustaffsson, discloses a seat-back tiltadjustment mechanism wherein ring gears are provided on the two hingeplates. In one embodiment there is one planetary gear mounted on acarrier and engaged with both ring gears. This works theoretically, butis impractical for the same reasons as the Recaro construction havingone planetary gear, i.e., it would be insufficiently strong to supportthe force exerted by a person leaning on the backrest of the seat.Gustaffsson also describes an arrangement wherein the carrier carriesthree planetary gears. This is also impractical for other reasons. Therehas to be a difference of three teeth between the two ring gears andwith the construction illustrated there should be a movement of 30degrees between the plates for each revolution of the control knob. Theforce needed to do this is far too large for an average person.Furthermore, the arrangement would not be self-locking and the backrestwould collapse in use. A large increase in the number of teeth on thering gears would avoid these problems, by reducing the angular movementof the hinge plates per revolution of the control knob, but then theteeth would be too weak for the purpose and also the gears would be fartoo expensive to produce. Cheaper methods such as fine blankingtechniques not being possible.

The above and other problems inherent in the prior art are solved by thepresent invention which provides an improved seat reclining mechanism.

SUMMARY OF THE INVENTION

In accordance with this invention, a seat reclining mechanism comprisesfirst and second hinge plates for mounting on a seat and back restrespectively, an internally toothed ring gear on each of the hingeplates, one ring gear having more teeth than the other ring gear. Adrive gear extends within the two ring gears, and means is providedengaged between the drive gear and the ring gears and including at leastone planetary gear in mesh with both ring gears and the control drivegear. Further, means are provided for rotating the drive gear to effectrelative angular adjustment of the two hinge plates. The means engagedbetween the drive gear and the ring gears may include rollers, butpreferably includes a plurality of planetary gears.

In another embodiment of the seat reclining mechanism of the presentinvention, the drive gear is also positioned within the space within thepair of ring gears. The drive gear is mounted on a shaft. The drive gearis sandwiched between a pair of carrier members each having a centralaperture complementary to the shaft so that it can freely rotate on theshaft. Each of the carrier members includes a plurality of partiallycircular, equi-angularly spaced openings which form a plurality ofradially extending arms having substantially concave surfaces extendingbetween neighboring arms. Planetary gears are snugly received betweenneighboring arms and are in contact with the concave surfaces of thecarrier members and meshed with the drive gear and with both of the ringgears. The floating nature of these carrier members compensates for anywear on the gears and for manufacturing tolerances. Furthermore, theconcave surfaces of the support positions of the carrier membersfunction as ramps so that the planetary gears tend to climb thesurfaces, which thereby tends to urge the planetary gears into mesh withthe ring gears so that no slippage occurs.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a first embodiment of a seat recliningmechanism according to the invention, shown in its position of use on avehicle seat;

FIG. 2 is an exploded perspective view of the seat reclining mechanismaccording to the invention on an enlarged scale with certain parts showncut away in order to reveal important details.

FIG. 3 is a side view of the seat reclining mechanism;

FIG. 4 is a sectional view of the seat reclining mechanism taken on theline IV--IV of FIG. 3;

FIG. 5 is a cross-sectional view of a second embodiment of the seatreclining mechanism of the present invention; and

FIG. 6 is an elevational view of the second embodiment of the inventionalong the line A--A of FIG. 5.

FIG. 7 is an exploded view of the second embodiment appearing in FIGS. 5and 6 of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a vehicle seat is shown having a seat 11 and aback-rest 12, the back-rest being angularly adjustable verticallyrelative to the seat 11. Adjustment is effected by a first embodiment ofthe seat reclining mechanism 10 of the present invention, which includesa first hinge plate 14 hinged to a second hinge plate 15. The firsthinge plate is mounted on the back-rest 12 and the second hinge plate 15is mounted on the seat 11. A knob 17 is provided, the rotation of whicheffects adjustment of the inclination of the back-rest. Further, hingeplates may be provided on the opposite side of the seat, but these neednot have the adjustment control. The hinge axis of the plates 14 and 15is coaxial with the inclination axis of the back-rest.

Referring to FIG. 2, the first hinge plate 14 is integrally formed witha first ring gear 20 having inwardly directed teeth 21. The hinge plate14 defines a coaxial recess 29 adjacent the ring gear 20. The secondhinge plate 15 is provided with a second ring gear 22 also havinginwardly projecting teeth 23. The second ring gear 22 has an annularboss 25 coaxial with the teeth 23 and boss 25 rotatably engages in arecess 26 in the second hinge plate 15. The second hinge plate 15 isnormally fixed with respect to the second ring gear 22 by means of alever arrangement 28, which is described fully hereafter. The secondring gear 22 also has a recess 27 and the first ring gear 20 rotatablyengages in the recess 27.

The recess 29 of the first hinge plate receives and locates a carrier33. The carrier has pressed-out projections 33a, 33b, 33c, and 33d. Acontrol gear assembly 35 is provided comprising a drive gear 34 providedwith a head 36. The drive gear 34 carries a complementary washer 37 andresilient packing 38. Packing 38 may include a resilient rubber "o"ring.

The drive gear 34 extends through an aperture 40 in the carrier 33 andthrough an aperture 41 in the second hinge plate 15. A further washer 42is received by the drive gear 34 to consolidate the carrier and hingeplates between the bolt 43 and the head 36.

Before assembly, four planet gears 45-48 are rotatably engaged withrespective projections 33a and 33d and are meshed with the drive gear34, each planet gear also meshing with both of the ring gears 20, 22. Itcan be seen that due to the resilient nature of the packing 38, carrier33 is slightly adjustable axially to compensate for material thicknessinaccuracies. Accordingly, upon use, the user feels a soft, springyresponse to hand actuation of a knob 17, instead of the jolting typesensation that would be felt if axial adjustment of carrier 33 wereprovided. The first ring gear 20 has more teeth than the second ring 22,the first ring gear having twenty-five teeth 21 and a second ring havingtwenty-one teeth 23. The addendum circle defined by each set of teeth21, 23 is the same and it will be appreciated that there are fourpositions where teeth of the two sets are aligned. Each planetary gearis located at one of these positions. Hence, where the difference in thenumber of teeth is three instead of four, three planetary gears would beprovided. It is envisaged that only one planetary gear need be provided,but other support means, such as rollers, would be required between thedrive gear 34 and the ring gears 20, 22.

The knob 17, in the form of a hand wheel is fixed to the control gearassembly by a bolt 51 and a washer 52, the bolt engaging in a threadedaperture 53 in the drive gear 34.

Hence rotation of the hand wheel 17 causes accompanying rotation of thedrive gear 34 and of the planetary gears 45-48, the latter rotating bothabout their own axes and about the control gear axis. The ring gears 20,22 are thereby caused angularly to move relatively to each other. Ineffect, the alignment positions of the teeth 21, 23 move slowly aroundthe main hinge axis. Accordingly, the hinge plates 14, 15 are movedangularly toward or away from each other, depending on the direction ofrotation of the hand wheel 17, producing adjustment of the inclinationof the back-rest 12.

In a vehicle having no rear doors, it is necessary for the back-rest totilt forwardly to permit access to the rear of the vehicle. Provisionsfor such tilting, independently of the gear arrangement described above,is provided by the lever arrangement 28.

A stop 67 is provided, which can cooperate with one of two projections75, 76 on the hinge plate 14 to define the extreme limits of relativeangular movement of two hinge plates 14, 15. It also cooperates withprojection 62 (FIG. 3) to prevent rearward tilting movement.

In addition the ring gear 22 has a projection 61 which engages with theend of an arm 63, the arm serving as a stop to prevent forward tiltingof the back-rest, i.e., clockwise angular movement of the hinge plate14, as seen in FIG. 3. The arm 63 is spring-urged into engagement into aprojection 61 by a spring 66 engaged between a lever 68 and the hingeplate 15. The lever 68 has a tongue 71 on a portion 70 engaged in anaperture 71a of the arm for movement of the lever with the arm, both thelever 68 and the arm 63 being pivoted about a common pivot member 65.The lever has a further portion 69 also provided with a tongue 69a whichengages in an elongated slot 77 in the hinge plate 15. This slot 77limits movement of the lever. A rivet 60 is provided on which the arm 63slides. Rocking of the lever disengages the arm 63 from the projection61 to permit forward tilting of the back-rest. In practice, the levermay be rocked by actuation from a remote position, by connection of anactuator with the lever 68 by a linkage or cable.

Referring to FIGS. 5 and 6, a second embodiment of the seat recliningmechanism of the present invention is designated as 100. The secondembodiment of the present invention 100 is very similar in its operationto that of the first embodiment of the present invention. Adjustment toa vehicle seat as shown in FIG. 1, is effected by the seat recliningmechanism 100 having a first hinge plate 160 hinged to a second hingeplate 162 as in the first embodiment of the present invention. The firsthinge plate 160 is mounted on the back-rest 12 and second hinge plate162 is mounted on the seat 11. Through the rotation of a hand wheel 147adjustment is effected in the inclination of the back-rest 12. Furtherdetails of the second embodiment 100 of the present invention aresubsequently discussed.

The first and second hinge plates 160 and 162 are held together by ashaft 113 having a head 114, and a threaded end opposite head 114.

The first hinge plate 160 is integrally formed with a first ring gear118 having inwardly directed teeth 119. The first hinge plate 160defines a coaxial recess 117 adjacent to the ring gear 118 with acircular shoulder 116 laterally spaced from the circular recess 117 andalso opposite teeth 119 of the first ring gear 118. The second hingeplate 162 includes a second ring gear 122 also having inwardlyprojecting teeth 123. The second hinge plate 162 also defines a coaxialrecess 121 adjacent the second ring gear 122. As the first and secondhinge plates 160 and 162 are positioned in the seat reclining mechanism100, the shoulder 116 mates with and is snugly received in the recess121.

A circular disc-like plate 125 is between and adjacent head 114 of theshaft 113 and the surface of the second hinge plate 162 opposite therecess 121.

The shaft 113 includes two opposite flat portions designated as 128 and129. A drive gear 130 is mounted on the shaft 113 and includes anaperture complementary to that portion of the shaft 113 having theflattened portion 128 and 129. Thus, rotation of the shaft 113 willconsequently produce a rotation of the drive gear 130.

Meshed between the first and second ring gears 118 and 122 and the drivegear 130 are means for engaging the drive gear and the ring gears whichis typically a plurality of planetary gears 135. The planetary gearssimultaneously engage both ring gears 118 and 122. For the purpose ofdescribing the present embodiment 100, four planetary gears are shown.

The control gear 130 is in contact with and sandwiched between a pair ofcarrier members designated as 131a and 131b. Each of the carrier membersis substantially flat and plate like and having a central aperture 150which is complementary to the shaft diameter so that the shaft 113 canrotate freely about the pair of carrier members 131a and 131b.Furthermore, each of the carrier members has a plurality of partiallycircular, equi-angularly spaced openings which form a plurality ofradially extending arms 151 with substantially concave surfaces 156extending between neighboring arms. Each of the planetary gears 130 issnugly received between neighboring arms and is in contact with theconcave surfaces 156. Thus, the carrier members 131a and 131b with thereconcave surfaces 156 and radially extending arms 151 separate theplanetary gears 135. For example, four arms 151 separate the planetarygears 135 from each other and support and locate the planetary gearswithin the mechanism 100. In the operation of the reclining mechanism100, the concave surfaces 156 tend to function as ramps so that theplanetary gears 135 tend to climb the concave surfaces, this tendencyserving to urge the planetary gears into mesh with the first and secondring gears 118 and 122, so that there is no slipping of the meshinggears even after considerable wear has occurred. Thus, the floatingnature of the carrier members 131a and 131b compensates for wear on thegears and for manufacturing tolerances.

A retaining plate 140 has a centrally-located aperture so that it isreceived by the shaft 113. The retaining plate 140 fits snugly into thecircular recess 117, thereby holding the gears in position. A resilientwasher 141 having an inside diameter much larger than the diameter ofthe shaft 113, is located on the retaining plate 140 with the shaftextending therethrough, and a spacer 142 fits snugly into the apertureof the resilient washer 141 and is received by the shaft 113. A locationwasher 143 is also received by the shaft 113 and is in contact with thespacer 142. The location washer 143 is formed having an outwardlyextending flange 136 along its outer periphery. A first and secondwasher 145 and 146 is received by the shaft 113 and with a nut 144,which is screwable on the threaded end of the shaft 113, bears onto thelocation washer 143. The washers 145 and 146 are of a small diametersuch that they bear down onto the central portion of the location washer143.

A hand wheel 147 having a central opening from which extends thethreaded ends of the shaft 113 is mounted on the location washer 143,and mates with the flange 136. The hand wheel 147 is retained onto themechanism 100 by a retaining washer 148 and by a nut 149 which screwablyengages the threaded end of the shaft 113.

Since the example of the present invention includes four planetary gears135, each of the carrier members 131a and 131b are of a substantiallycross-like configuration.

In the operation of the second embodiment of the present invention, theresiliency of the resilient washer 141 permits rotation of the shaft 113by the turning of the hand wheel 147. The drive gear 130 is therebyrotated by the rotation of the hand wheel 147, and this motion isconsequently transmitted through the planetary gears 135 to the ringgears 118 and 122 so that a small angular movement of the hinge plates160 and 162 is effected per rotation of the hand wheel 147. Thus, inoperation the second embodiment 100 is, in essence, the same as thefirst embodiment 10. However, unlike the first embodiment, the secondembodiment includes a pair of carrier members 131a and 131b whichsupport and locate the planetary gears 135 in meshing relationship withthe first and second ring gears 118 and 122 and the drive gear 130. Ofmost significance, these carrier members 131a and 131b provide thismeshing by a floating nature which prevents slipping even when the gearshave had considerable wear and thus compensates for wear on the gearsand for manufacturing tolerances.

It is anticipated that the second embodiment of the present inventionwill utilize the same means for tilting forward the back-rest as shownin the first embodiment, i.e., lever arrangement 28.

For the purpose of describing the second embodiment 100 of the presentinvention, it is assumed in a typical structure the first ring gear 118will have twenty-five teeth and the second ring gear 122 will havetwenty-one teeth while each of the four planetary gears will have eightteeth. Also for the purpose of discribing the second embodiment it isassumed that the drive gear 130 is about one-third the thickness of theplanetary gears 135 and that the carrier members 131a and 131b are ofsubstantially the same thickness and also about one-third the thicknessof the planetary gears 135.

Although this invention has been described with reference to specificembodiments thereof, it will be appreciated that various othermodifications may be made, including the substitution of equivalentcomponents for those shown and described. Further, the inventioncomprehends the use of certain features independently of other features,and the substitution of equivalent elements, all of which modificationsmay be made without departing from the spirit or scope of the inventionas defined in the appended claims.

I claim:
 1. Seat reclining apparatus comprising:a. first and secondinternally toothed coaxial ring gears, respectively fixedly connected tobench and back portions of said seat rotatable circularly with respectto one another about a common axis to rotate said seat back with respectto said seat bench, one of said ring gears having more teeth than theother; b. a drive gear rotatable circularly coaxially with and spacedinteriorly of said ring gears; said common axis of said drive and ringgears being stationary; c. means for rotating said drive gear; d. atleast one planetary idler gear engaging said drive gear and both of saidring gears at a common angular position, each said planetary idler gearrotating about an axis which is parallel to the common axis of saiddrive and ring gears, each said planetary idler gear axis rotatingcircularly about said common axis as each said planetary idler gear isrotatably driven by said drive gear and concurrently engages said tworing gears thereby rotating said ring gears coaxially with respect toone another; e. positioning means, interposed between said drive andring gears, rotatable with said at least one planetary idler gear aroundsaid drive gear about said common axis for maintaining said at least oneplanetary idler gear in driving contact with said drive gear and saidring gears thereby enabling said ring gears to rotate coaxially withrespect to one another; and f. at least one carrier member movablerelative to said shaft and extending between said at least one planetarygear and said positioning means, each said carrier member having aplurality of surfaces facing and adapted for contacting a portion of theperiphery of a respective one of said at least one planetary gear andsaid positioning means to maintain said at least one planetary gear andsaid positioning means in spaced relationship as they rotate. 2.Apparatus of claim 1 wherein drive gear axial length is greater thanthat of said planetary idler gears.
 3. Apparatus of claim 2 wherein saidpositioning means is interposed between and facingly contacts mutuallyfacing toothed surfaces of said drive and ring gears.
 4. Apparatus ofclaim 3 wherein said positioning means contact said ring gears at anumber of positions one less than the difference in the number of teethof said respective ring gears.
 5. Apparatus of claim 4 wherein saidpositioning means and said planetary gears collectively contact saidring gears at points symmetrically spaced about said common axis ofrotation.
 6. Seat reclining apparatus comprising:a. first and secondinternally toothed coaxial ring gears, respectively fixedly connected tobench and back portions of said seat, rotatable circularly with respectto one another about a common axis to rotate said seat back with respectto said seat bench, one of said ring gears having more teeth than theother; b. a drive gear rotatable circularly coaxially with and spacedinteriorly of said ring gears; said common axis of said drive and ringgears being stationary; c. means for rotating said drive gear; d. aplurality of identical planetary idler gears, each engaging said drivegear and both of said ring gears at common angular positions so thatsaid drive gear, said plurality of planetary idler gears and said ringgears rotate serially, each planetary idler gear being rotatable about acentral axis paralleling said drive and ring gear common axis, saidplanetary idler gear axes rotating circularly about said common axis assaid planetary idler gears are rotatably driven by said drive gear andconcurrently engage said two ring gears thereby rotating said ring gearscoaxially with respect to one another; said planetary gears beingsymmetrically spaced about the common axes of the drive and ring gearsand collectively contact the drive and ring gears at pointssymmetrically spaced about the common axes of rotation of the drive andthe ring gears; and e. at least one carrier member movable relative tosaid shaft and extending between said planetary gears, each said carriermember having surfaces facing and adapted for contacting a portion ofthe periphery of at least one of said planetary gears to maintain saidplanetary gears in spaced relationship as they rotate.
 7. Apparatus ofclaim 6 wherein said drive gear has an axial greater than axial lengthsof said planetary idler gears.